This Invention is a dimming adjustable discharge lamps power source device with voltage amplitude control function which is controlled by a positive or negative logic control, the high frequency transformer of the circuit gives high voltage power source and the multiple secondary winding of the transformer give stable DC power source supply, protection, over current, over voltage, and etc. function through rectify, filtering, voltage regulator, and etc. devices, above embodiment is applied in TFT LCD TV, LCD monitor, LCD TV Wall, LCD brightness control, power of PDP TV, and DC power source supply and secures safety.
The brightness control of Cold Cathode Fluorescent Lamp, CCFL, External Electrode Fluorescent Lighting, EEFL used to be Pulse Frequency Modulation, PAM, or Pulse Width Modulation, PWM methods to achieve CCFL, EEFL lamps group dimming control, the disadvantage of these methods are,
1. PFM, the amplitude is fixed, the frequency is variable, and the variable frequency causes lot of noise interference.
2. PWM, The frequency is fixed, the width of the pulse is variable, the method makes hum noise and it used to be applied to low voltage application, such as Inverter.
This Invention has a fixed frequency and pulse width; by adjust the amplitude of DC Voltage to achieve brightness control, moreover it provides stable DC power source supply to system to solve above disadvantage of PAM and PWM.
The first purpose of this Invention is to give CCFL, EEFL lamps group a fixed frequency and pulses width power source.
The second purpose of this Invention is to provide a (Voltage Amplitude Method, VAM) method to solve the noise, hum, and high cost of PWM and PAM methods.
The third purpose of this Invention is to provide brightness control to discharge lamps of TFT LCD TV, LCD Monitor, LCD TV Wall, PDP TV, and etc monitors.
The forth purpose of this Invention is to provide a (Voltage Amplitude Method, VAM) method to generate a variable DC power source supply to give other application in system.
The fifth purpose of this Invention is to provide a high frequency and high wattage output which is couple from a half bridge oscillation driver, one or multi-sets of MOSFETs, one or more output high frequency transformers to match power requirement of TFT LCD TV, LCD Monitor, LCD TV Wall, PDP TV, and etc monitors.
The sixth purpose of this Invention is to provide an impulse width control circuit to control brightness of a CCFL and EEFL lamps group in or out of the glow zone and DC voltage control of the DC power source supply.
The seventh purse of this Invention is to offer better circuit to prove this embodiment.